Recent findings suggest that approximately one-quarter of infants with suspected or confirmed Zika virus exposure during the 2015-2016 Rio de Janeiro outbreak developed eye abnormalities. Researchers said that regardless of laboratory confirmation, all infants born during Zika outbreaks “should be universally screened for eye abnormalities.”
Irena Tsui, MD, an ophthalmologist at UCLA, and colleagues wrote that lab confirmation of Zika virus (ZIKV) infection in neonates may be difficult for several reasons, including the observation that many cases of ZIKV infection are asymptomatic. These cases, according to the researchers, tend not to get tested for the infection. Additionally, a negative test result cannot rule out infection because the virus is detectable through testing for only 3 to 16 days after symptom onset.
“Interpretation of serologic assays is confounded by cross-reactivity with pre-existing dengue antibodies, dengue being a common infection in endemic areas,” the researchers wrote. “Therefore, the lack of laboratory confirmation of ZIKV infection is a commonly encountered clinical scenario, and information regarding eye manifestations in this population is needed to guide screening recommendations.”
Tsui and colleagues analyzed the characteristics of infants referred for evaluation at the Instituto Fernandes Figueira during the 2015-2016 Zika outbreak in Rio de Janeiro. Pediatric ophthalmologists conducted complete eye exams between January 2016 and February 2017.
Reverse-transcriptase PCR testing was conducted to confirm ZIKV infection in 189 infants. Of the 224 infants referred for evaluation, 156 were positive based on blood, urine or placental samples. Microcephaly was found in 62 infants, and 90 had central nervous system abnormalities.
The researchers said eye abnormalities were found in 25.4% of infants. Optic nerve (77.2%) and retina (64.9%) abnormalities were most commonly reported.
According to Tsui and colleagues, infants with suspected ZIKV infection had more eye (36.8% vs. 20.5%) and central nervous system abnormalities (68.3% vs. 28.1%) compared with infants with confirmed infection, but the researchers speculated that this was most likely caused by referral patterns.
Notably, eye abnormalities consistent with ZIKV infection were “clinically comparable” in both confirmed and unconfirmed cases, the researchers said.
“Because universal eye screening for ZIKV endemic areas has not yet been adopted, it is difficult to assess the true frequency of eye abnormalities in ZIKV-exposed infants,” they wrote. “We believe all infants with potential ZIKV exposure (ie, all infants born during outbreak periods in endemic areas) should have screening eye examinations regardless of the presence of microcephaly, other CNS abnormalities, or laboratory confirmation of infection.” – by Katherine Bortz
Disclosures: The authors report no relevant financial disclosures.